(April 24, 2024)
The age of the Earth’s magnetic field remains under question in part because we don’t fully understand what causes it today. We know it is a product of movements in the molten outer core, whose high iron content turns convection currents into a dynamo, and these currents in turn are produced by the solidification of the inner core.
(06.07.2020)
Rapid changes in field direction have also attracted significant attention, particularly in the context of polarity reversals18. Historically, the fastest directional changes were attributed to lava flows at Steens Mountain, though these results are now thought to be untenable19. Currently, the fastest directional changes noted are those recorded by sediments in central Italy20, where angular changes in the Virtual Geomagnetic Pole position (P^V) reach values of ∂P^V/∂t∼1∘yr−1. These rates are about a factor of 10 faster than values of ∂P^V/∂t∼0.1∘yr−1 for the modern field, similar to the difference in rates of intensity change between the modern field and spikes.
(06.07.2020)
The clearest example of this in their study is a sharp change in the geomagnetic field direction of roughly 2.5 degrees per year 39,000 years ago. This shift was associated with a locally weak field strength, in a confined spatial region just off the west coast of Central America, and followed the global Laschamp excursion — a short reversal of the Earth‘s magnetic field roughly 41,000 years ago.